The present invention relates to a high-speed filling machine for filling a liquid, such as juice or milk, into containers at a high speed.
Liquid filling machines are already known which comprise a machine frame having a filling station, a conveyor for transporting containers so as to successively stop them at the filling station, a filling device disposed at the station, and means for supplying the liquid to be filled into the device.
Also known, as such machines, are a packaging machine having two filling stations along a container transport path (Unexamined Japanese Utility Model Publication No. 10108/1994), and an apparatus for practicing a method of filling a liquid of high viscosity, such as adhesive or sealing material, into containers with high accuracy without necessitating an increased time, by using two filling stations (JP-A-48393/1996).
It appears possible to improve filling machines in the filling capacity by making the machine operable at a higher speed. The higher speed shortens the operating cycle of the machine to reduce the filling time per container, consequently giving rise to a need to fill the liquid into the container within the reduced time in an amount corresponding to the capacity of the container. It then becomes necessary to fill the liquid at an increased flow rate, which entails the problem that the liquid will bubble up or form a disturbed surface within the container. For this reason, it has been difficult to operate the machine at an increased speed.
The liquid filling-packaging machine disclosed in the foregoing publication No. 10108/1994, although having the primary and secondary filling devices, is not provided with supply means for supplying the same liquid to be filled into the two filling devices, nor has the machine control means for controlling the amount to be filled in by the primary device and the amount to be filled in by the secondary device so that the combined amount to be filled in by the two devices is equal to the capacity of the container. The machine is therefore useful when two kinds of liquids are to be separately filled into each container, whereas the machine is not usable for operation at a higher speed.
With the apparatus of JP-A-48393 adapted to fill a highly viscous liquid into containers with high accuracy, a primary channel and a secondary channel for feeding the liquid respectively to the primary filling station and the secondary filling station therethrough are set at a flow rate ratio of 90:10 to 99.5:0.5, preferably 99:1, such that a very small amount of the liquid is slowly filled in at the secondary station to accurately compensate for a deficiency in the contents of the container which has been filled at the primary station approximately to a specified amount. However, the apparatus requires means for detecting the amount filled in to accurately compensate for the deficiency in the contents of the container filled approximately to the specified amount at the primary station. Furthermore, it is required that the container stopped by an intermittent drive conveyor be held completely at a halt to eliminate the disturbance of the liquid surface therein for the accurate detection of the amount of liquid filling the container. Although adapted to accurately fill containers with the specified amount of contents, the apparatus is unable to accurately fill the specified amount of liquid into the containers at a higher speed.